The purge of thousands in the Turkish military in the aftermath of an attempted coup has not weakened the country's military, NATO Secretary-General Jens Stoltenberg said on Wednesday.

"Turkey has a large armed force, professional armed forces and ... I am certain they will continue as a committed and strong NATO ally," Stoltenberg told Reuters in an interview on the sidelines of a meeting of defense officials from more than 30 countries involved in the coalition against Islamic State.

Some 60,000 soldiers, police, judges, civil servants and teachers have been suspended or detained since the military coup attempt, increasing tension across the country of 80 million that borders Syria's chaos and is a Western ally against Islamic State.

About a third of Turkey's roughly 360 serving generals have been detained since the failed coup on July 15.

The armed forces last used force to stage a successful coup in Turkey more than 30 years ago.

On Wednesday, Dutch, German and Canadian foreign ministers expressed concern about the scale of the crackdown by Turkish authorities and called on Turkey to respect the rule of law.

Stoltenberg said he expected Turkey's reaction to the coup attempt to be proportionate and in line with the values of NATO, adding that there were no talks to reconsider Turkey's membership in the military alliance.

"It is important for all of us that Turkey continue to be a strong NATO ally because Turkey is on the border of all the instability, all the violence we have seen in Iraq and Syria," Stoltenberg said.

Speaking with reporters after the defense ministers meeting at Joint Base Andrews outside Washington, U.S. Defense Secretary Ash Carter said the meeting focused on what happens after the defeat of Islamic State in terms of stabilization and reconstruction.

Stoltenberg said there was a greater need to share intelligence in general within NATO and specifically in respect to the fight against the militant group Islamic State.

"Partly we need ... to collect more intelligence and partly we need to have better routines, better mechanisms for sharing intelligence as soon as possible," Stoltenberg said.